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<html lang="en">
<head>
    <meta charset="UTF-8">
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    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    年龄:<input type="text" />
    <button class="prev">上一步</button><button>完成注册</button>
    <script>
        document.querySelector(".prev").onclick = function(){
            window.location.href="register1.html";
        }



    </script>
</body>
</html>